usrloc: Fix matching_mode regression in 3aae7e6

Commit 3aae7e6 did too many things at once, including the refactoring
of CT_MATCH_NONE from -1 to 0 (along with all other enum members!),
causing a mismatch of this module parameter with its documentation, and
leading to failed startup checks under ul_init_globals().

Credits to @98oi98 for the report!

Fixes #2337

(cherry picked from commit dc8cfe8)

modules/usrloc/ucontact.h

@@ -86,7 +86,7 @@ typedef uint64_t ucontact_id;
 
 struct ct_match {
 	enum {
-		CT_MATCH_NONE,
+		CT_MATCH_NONE=-1,
 		CT_MATCH_CONTACT_ONLY,
 		CT_MATCH_CONTACT_CALLID,
 		CT_MATCH_PARAMS,